Sectional Flooring with Coupling Member, and Assembling Method Thereof

ABSTRACT

Sectional flooring is provided. The sectional flooring includes first, second, and third floor boards ( 10,20  and  30 ) and a coupling member ( 40 ) for connecting the first and second floor boards ( 10  and  20 ) that are arranged to be adjacent to each other in a longitudinal direction. The coupling member ( 40 ) includes a base portion ( 41 ) placed over-adjacent first and second floor boards ( 10  and  20 ), a pair of side hooks ( 42 ) protruding from opposite ends of the base portion ( 41 ) toward top surfaces of the first and second floor boards ( 10  and  20 ), and a pair of cantilever hooks ( 43 ) spaced apart from each other by a predetermined distance and protruding from a center of the base portion ( 41 ). Each of the cantilever hooks ( 43 ) includes a hook step ( 431 ). The hook step ( 431 ) includes an upper portion formed with an inclined surface inclined at a predetermined lead angle (OL) and a lower portion is formed with an inclined surface inclined at a predetermined return angle (OR).

TECHNICAL FIELD

The present invention relates to sectional flooring. More particularly,the present invention relates to sectional flooring with a plurality offloor boards that can be securely coupled to each other by an elasticcoupling member, and a method of assembling the same.

2. BACKGROUND ART

Generally, sectional flooring is formed with a plurality of floor boardseach having a predetermined dimension, which are made separately, andassembled together on the floor of a building. In the conventionalsectional flooring, each of the floor boards is formed in a rectangularshape having a pair of longitudinal sides and a pair of lateral sides.Each of the floor boards is provided at longitudinal or lateral sideswith a coupling structure by which the floor board can be coupled toanother floor board.

That is, the coupling structure includes at least one protrusion and atleast one recess. Therefore, the two adjacent floor boards are assembledwith each other by the coupling structure formed with the protrusion andthe recess and fixed to the floor of the building using an adhesiveapplied to a bottom of the floor boards. However, such a fixingtechnique has disadvantages in that it is difficult to remove the floorboards from the floor of the building, and an epoxy-based adhesive thatis harmful to the human body should be used.

It has been proposed that the adhesive be further applied to the sidesof the floor boards with the protrusions and grooves to simultaneouslyutilize the mechanical assembling force between the protrusions and thegrooves and the adhesion force of the adhesive in assembling twoadjacent floor boards. This assembling structure is generally called asuspension-type structure and involves advantages in that the floorboards can be easily installed and removed from the floor of thebuilding. However, in case the adhesive is frozen or used afterlong-term storage, the adhesion force of the adhesive is deteriorated.Further, when the adhesive is not properly applied to the floor boards,a gap or a stepped difference may be formed between the floor boards.

DISCLOSURE OF INVENTION Technical Problem

Therefore, as a modified structure of the suspension-type structure, astructure where the two adjacent floor boards are assembled together bya locking member instead of the adhesive has been recently proposed.With regard to this structure, each of U.S. Pat. No. 4,426,820 andJapanese Laid-Open Patent No. H3-169967 discloses a sectional flooringhaving a locking member provided on a side of a floor board.

However, in this modified structure using the locking member, the floorboards that are generally wood panels, medium density fiberboard, orhigh density fiberboard may contract because of floor heating due to amaterial property thereof. The contraction of the floor boardsdeteriorates the coupling force of the locking member, resulting in agap between the floor boards.

Furthermore, the wood panels, medium density fiberboard, and highdensity fiberboard have lower elasticity as compared with floor boardsthat are formed of synthetic resin. Therefore, when the floor boards areassembled together through a snap-in method, a portion of the lockingmember on which the force is concentrated may be easily damaged.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

Technical Solution

The present invention has been made in an effort to provide sectionalflooring that can prevent a gap or stepped difference from occurringbetween floor boards by enhancing a coupling force between the floorboards even when the floor boards contract because of the floor heating,and an assembling method thereof.

The present invention also provides sectional flooring that can improvethe endurance of floor boards by preventing a coupling portion betweenthe floor boards from being damaged.

In an exemplary embodiment of the present invention, a sectionalflooring includes first, second, and third floor boards each having acore formed of wood, the floor boards being provided at longitudinal andlateral sides with coupling structures and assembled together, and acoupling member for connecting the first and second floor boards thatare arranged to be adjacent to each other in a longitudinal directionthereof, the coupling member being coupled to lower portions of thelateral sides of the first and second floor boards. The coupling memberincludes a base portion placed over the adjacent first and second floorboards; a pair of side hooks protruding from opposite ends of the baseportion toward top surfaces of the first and second floor boards, theside hooks being fitted in the lateral sides of the first and secondfloor boards to endure a stress applied in a longitudinal direction ofthe first and second floor boards; and a pair of cantilever hooks spacedapart from each other by a predetermined distance and protruding from acenter of the base portion toward the top surfaces of the first andsecond floor boards, each of the cantilever hooks including a hook stepengaged with the lateral side of the corresponding one of the first andsecond floor boards and an inclined portion extending downward from thehook step, the cantilever hooks supporting a stress applied in athickness direction of the floor boards. Each of the hook steps includesan upper portion formed with a surface inclined at a predetermined leadangle θ_(L) with respect to a vertical line extending in the thicknessdirection of the first and second floor boards, and a lower portionformed with a surface inclined at a predetermined return angle θ_(R)with respect to a horizontal line extending in a length direction of thefirst and second floor boards.

The lead angle θ_(L) may be 5°-45° and the return angle θ_(R) may beequal to or less than 60°.

Each of the first and second floor board may include a first recessportion for receiving the side hook, the first recess portion beingformed on a lower portion of the lateral side, which faces the couplingmember; a coupling protrusion protruding from a side of the first recessportion toward the lower portion thereof and fitted between the sidehook and the cantilever hook; a second recess portion that is providedon a side of the coupling protrusion, which faces an outer side of thefloor board, to receive the hook step of the cantilever hook; and aprojection for guiding a motion of the cantilever hook, the projectionbeing formed with an inclined portion on a lower portion of the secondrecess portion.

A cavity for receiving thermal expansion of the coupling member may beformed between the first and second floor boards and a coupling surfaceof the coupling member. Particularly, a width “a” of the cavity betweenthe coupling member and the first and second floor boards at a topsurface of the base portion of the coupling member and the cantileverhook is 0.05˜0.20 mm, and a width “b” of the cavity between the couplingmember and the first and second floor boards at an outer surface of theside hook is 0.05-0.50 mm.

An upper portion of the lateral side of each of the first and secondfloor boards, which does not face the coupling member, may be formedwith a vertical surface, and the vertical surfaces of the first andsecond floor boards may contact each other.

The first floor boards may be provided at a longitudinal side with anupper hook step protruding toward the third floor board, an intermediatehook step protruding from a bottom of the upper hook step toward abottom surface thereof, and a fourth recess portion provided at a sideof the intermediate hook step, which faces an inner portion thereof, andthe third floor boards is provided at the longitudinal side with a fifthrecess portion for receiving the upper hook step, a sixth recess portionfor receiving the intermediate hook step, and a lower hook step thatextends from the sixth recess portion to an external portion thereof andis received in the fourth recess portion.

In another exemplary embodiment of the present invention, a method ofassembling the sectional flooring includes assembling the floor boardwith the coupling member, interconnecting the longitudinal sides of thefirst and third floor boards by rotating the first floor board downwardafter fitting the upper hook step of the first floor board into thefifth recess portion of the third floor board, and interconnecting thelateral sides of the first and second floor boards by assembling thefirst floor board with the coupling member by pressing the first floorboard downward.

ADVANTAGEOUS EFFECTS

According to the present invention, since the lateral sides of the floorboards are coupled to each other by the coupling member having theabove-described structure and material property, the coupling forcebetween the flooring boards can be enhanced and thus the gap and stepdifference between the floor boards can be suppressed even when thefloor boards can contract because of floor heating. Furthermore, sinceno damage such as a crack occurs on the coupling portion during theassembling process of the sectional flooring, the endurance of thesection flooring can be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial top view of a sectional flooring according to afirst exemplary embodiment of the present invention.

FIG. 2 is a sectional view taken along line I-I of FIG. 1.

FIG. 3 is an exploded sectional view of FIG. 2.

FIG. 4 is an enlarged view of a coupling member depicted in FIG. 3.

FIG. 5 is a sectional view taken along line II-II of FIG. 1.

FIG. 6 is a partial sectional view of the sectional flooring of FIG. 1,illustrating an assembling process of longitudinal sides of floorboards.

FIG. 7 is a partial sectional view of the sectional flooring of FIG. 1,illustrating an assembling process of lateral sides of floor boards.

FIG. 8 is a partial sectional view of a sectional flooring according toa second exemplary embodiment of the present invention.

FIG. 9 is a partial sectional view of a sectional flooring according toa third exemplary embodiment of the present invention.

FIG. 10 is a partial sectional view of a sectional flooring according toa fourth exemplary embodiment of the present invention.

FIG. 11 is a partial sectional view of a sectional flooring according toa fifth exemplary embodiment of the present invention.

MODE FOR THE INVENTION

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. The invention may, however, be embodied inmany different forms and should not be construed as being limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the concept of the invention to those skilled in the art.

FIG. 1 is a partial top plan view of sectional flooring according to afirst exemplary embodiment of the present invention.

Referring to FIG. 1, sectional flooring 500 according to an exemplaryembodiment of the present invention includes a plurality of floor boards10, 20, and 30 each having a pair of longitudinal sides 2 and a pair oflateral sides 4, and a plurality of coupling members 40. Thelongitudinal and lateral sides 2 and 4 are provided with couplingstructures. The coupling members 40 are provided between the lateralsides 4 of the floor boards 20, 30, and 30 to interconnect the floorboards 10, 20, and 30, which are arranged in a longitudinal direction (ay-direction in FIG. 1), by associating with the coupling structuresformed on the lateral sides 4 of the floor boards 10, 20, and 30.

Each of the floor boards 10, 20, and 30 has a core formed of wood. Eachof the floor boards 10, 20, and 30 is a rectangular panel having apredetermined thickness and area The floor boards 10, 20, and 30 may bewood panels, medium density fiberboard (MDF), or high density fiberboard(HDF). The floor boards 10, 20, and 30 may be coated with apre-impregnated foil or paint.

The coupling members 40 may be formed of a material that is similar tothe floor boards 10, 20, and 30 or a material having elasticity greaterthan the floor boards 10, 20, and 30. The coupling members 40 areprovided on the lateral sides of the floor boards 10, 20, and 30.Therefore, the two floor boards 10 and 20 that are arranged lengthwise(the y-direction in FIG. 1) are interconnected at their lateral sides 4by the coupling member 40.

The coupling structure provided on the lateral sides of the first andsecond floor boards 10 and 20 will be described with reference to FIGS.2, 3, and 4, and the coupling structure provided on longitudinal sidesof the first and third floor boards 10 and 30 will be described.

FIG. 2 is a sectional view taken along line I-I of FIG. 1, and FIG. 3 isan exploded sectional view of FIG. 2. FIG. 4 is an enlarged view of acoupling member depicted in FIG. 3.

Referring to FIG. 2 through FIG. 4, the coupling member 40 includes abase portion 41 having a predetermined width and a predeterminedthickness, a pair of side hooks 42 protruding from opposite ends of thebase portion 41 toward top surfaces of the first and second floor boards10 and 20, and a pair of cantilever hooks 43 spaced apart from eachother by a predetermined distance and protruding from a center of thebase portion 41 toward the top surfaces of the first and second floorboards 10 and 20.

A height H₂ (see FIG. 3) of each of the cantilever hooks 43, which ismeasured based on the top surface of the base portion 41, is greaterthan a height H₃ (see FIG. 3) of each of the side hooks 42. The pair ofside hooks 42 and the pair of cantilever hooks 43 are symmetricallyarranged with respect to an imaginary vertical line (broken line in FIG.3) passing through the center of the coupling member 40.

The bottom surface of the base portion 41 is located on the samehorizontal plane as the bottom surfaces of the first and second floorboards 10 when they are installed on the floor. An overall height H_(T)(see FIG. 2) of the coupling member 40 is less than a thickness T (seeFIG. 2) of each of the first and second floor boards 10 and 20, so thatthe coupling member 40 is not shown when viewed from the top of thesectional flooring.

The side hooks 42 may be perpendicular to the base portion 41 orinclined toward the cantilever hooks 43 at a predetermined angle. Theside hooks 42 resist against stress (mostly tension) applied in a lengthdirection (the y-direction in FIG. 4) of the first and second floorboards 10 and 20.

The cantilever hooks 43 are provided at an upper portion thereof withhook steps 431. A width of a portion of each of the cantilever hooks 43between the base portion 41 and the hook step 431 is gradually reducedas it goes away from the base portion 41. In a sectional view of thecantilever hooks 43, inner surfaces of the cantilever hooks 43, whichface the central line, are straight, and outer surfaces of thecantilever hooks 43, which face the side hooks 42, are defined byinclined portions 432.

A space defined between the cantilever hooks 43 provides a marginalspace required when the cantilever hooks 43 are biased toward the centerof the coupling member 40 during the coupling of the coupling member 40to the floor boards 10 and 20.

An upper portion of each of the hook steps 431 is formed with a surfacethat is inclined at a predetermined lead angle θ_(L) (see FIG. 4) withrespect to a vertical line extending in a thickness direction (az-direction in FIGS. 2 through 4) of the floor boards 10 and 20, and alower portion of each of the hook steps 431 is formed with a surfacethat is inclined at a predetermined return angle θ_(R) (see FIG. 4) withrespect to a horizontal line extending in a length direction (ax-direction in FIGS. 2 through 4) of the floor boards 10 and 20.

The upper portion of the hook step 431, on which the lead angle θ_(L) isdefined, functions to guide a motion of the cantilever hook 43 such thatthe cantilever hook 43 is biased toward the center of the couplingmember 40 rather than toward the side hook 42 when a force for pressingthe hook stop 431 downward and outward of the coupling member 40 isapplied by the floor boards 10 and 20 during the assembly of the floorboards 10 and 20 with the coupling members 40.

The cantilever hooks 43 are rocked and coupled to the coupling structureprovided on the first and second floor boards 10 and 20 to securelyinterconnect the floor boards 10 and 20. In addition, the cantileverhooks 43 resist against the stress applied in the thickness direction(the z-direction in FIGS. 2 through 4) of the floor boards 10 and 20 toprevent the floor boards 10 and 20 from being spaced apart from eachother and a step difference from occurring between the floor boards 10and 20. A maximum width H_(O)(see FIG. 3) may be less than a width W(see FIG. 3) of the side hook 42.

The first and second floor boards 10 and 20 are provided at lowerportions of the lateral sides thereof, which face the coupling member40, with first recess portions 11 and 21 receiving the side hooks 42,and at sides of the first recess portions 11 and 21, which face outersides of the floor boards 10 and 20, with coupling protrusions 12 and 22fitted between the side hooks 42 and the cantilever hooks 43.

At this point, projections 14 and 24 corresponding to the inclinedportions 432 of the cantilever hooks 43 are formed on sides of thecoupling protrusions 12 and 22, on which second recess portions 12 and23 are formed. That is, surfaces of the projections 14 and 24, whichface the coupling member 40, are inclined to correspond to the inclinedportions 432. The inclined surfaces of the projections 14 and 24together with the hook steps 431 of the cantilever hooks 43 function toguide a motion of the cantilever hooks 43 such that the cantilever hooks43 are biased toward the center of the coupling member 40 when thecoupling member 40 is assembled with the floor boards 10 and 20.

A stopper projection 15 is formed on an upper portion of the lateralside of one (the first floor board 10 in this exemplary embodiment) ofthe first and second floor boards 10 and 20. A third recess portion 25for receiving the stopper projection 15 is formed on an upper portion ofthe lateral side of the other (the second floor board 20 in thisexemplary embodiment) of the first and second floor boards 10 and 20.The stopper projection 15 and the third recess portion 25 function as astopper during the assembly of the coupling member with the first andsecond floor boards 10 and 20.

The stopper function allows the coupling member 40 to be effectivelyassembled with the floor boards 10 and 20 when the floor boards areinstalled on a floor having an uneven surface or on a soft material suchas Styrofoam.

FIG. 5 is a sectional view taken along line I-III of FIG. 1.

Referring to FIG. 5, the first floor board 10 is provided at alongitudinal side with an upper hook step 16 protruding toward the thirdfloor board 30. An intermediate hook step 17 protrudes from a bottom ofthe upper hook step 16 toward the first floor board 10, and a fourthrecess portion 18 is provided at a side of the intermediate hook step17, which faces an inner portion of the first floor board 10.

The third floor board 30 is provided at the longitudinal side with afifth recess portion 31 for receiving the upper hook step 16 of thefirst floor board 10, a sixth recess portion for receiving theintermediate hook step 17 of the first floor board 10, and a lower hookstep 33 that extends from the sixth recess portion 32 to an externalportion of the third floor board 30 and is received in the fourth recessportion 18 of the first floor board 10.

The following will describe an assembling process of the sectionalflooring with reference to FIGS. 6 and 7.

FIG. 6 is a partial sectional view of the sectional flooring of FIG. 1,illustrating an assembling process of the longitudinal sides of floorboards, and FIG. 7 is a partial sectional view of the sectional flooringof FIG. 1, illustrating an assembling process of lateral sides of floorboards.

Referring first to FIG. 6, the upper hook step 16 of the first floorboard 10 is first fitted into the fifth recess portion 31 of the thirdfloor board 30 at a predetermined angle, and subsequently the firstfloor board 10 rotates downward. Then, the upper and intermediate hooksteps 16 and 17 of the first floor board 10 are respectively fitted inthe fifth and sixth recess portions 31 and 32, thereby completing theassembling of the first and third floor boards 10 and 30.

Here, when the first floor board 10 rotates downward, the first floorboard 10 is placed on the coupling member 40 engaged with the secondfloor board 20. In this state, when the first floor board 10 is presseddownward, the first floor board 10 is engaged with the coupling member40 in a snap-in manner and is thus assembled with the second floor board20.

Referring to FIG. 7, as the first floor board 10 moves downward, theinclined upper portion of the hook step 431 of the cantilever hook 43contacts and slides over the inclined projection 14 of the first floorboard 10 and thus the cantilever hook 43 of the coupling member 40 canbe easily biased toward the center of the coupling member 40.Subsequently, as the first floor board 10 further moves, the cantileverhook 43 is restored such that the hook step 431 of the cantilever hook43 is fully engaged with the second recess portion 13 of the first floorboard 10.

After the above, the side hook 42 of the coupling member 40 is fitted inthe first recess portion 11 of the first floor board 10 and the couplingprotrusion 12 of the first floor board 10 is fitted between the sidehook 42 and the cantilever hook 43, thereby securely assembling thecoupling member 40 with the first floor board 10. At this point, a widthP of the coupling protrusion 12 may be 3.0 mm or more so that thecoupling protrusion 12 is not damaged by stress generated by thecontraction of the floor boards.

Further, the lead angle θ_(L) (see FIG. 4) of the hook step 431 of thecantilever hook 43 may range from 5° to 45°. When the lead angle θ_(L)is less than 5 or greater than 45°, the guide effect obtained by thesliding over the projection 14 of the first floor board 10 isdeteriorated. Therefore, it becomes difficult to effective guide themovement of the cantilever hook 43. The return angle θ_(R) (see FIG. 4)may be set to be 60° or less considering a frictional coefficient of acontact surface between the coupling protrusion 12 and the couplingmember 40.

The inclined portion 432 formed below the hook step 431 allows thecantilever hook 43 to be effective biased when the coupling member isengaged with the floor board. At this point, a ratio between a lower endwidth H_(O) (see FIG. 4) of the cantilever hook 43 facing the hook step431 and a lower end width H_(L) (see FIG. 4) of the hook step 431 may be2:1 so that the biasing of the cantilever hook 43 can be moreeffectively realized.

As described above, in the sectional flooring 500 according to thisexemplary embodiment of the present invention, the floor boards areassembled together through an insertion-and-rotation manner at thelongitudinal sides and through a snap-in manner at the lateral sides byusing the coupling member 40. Therefore, the installation of thesectional flooring 500 can be effectively performed with less ambientinterference.

With the above-described structure, the coupling member 40 may be formedof a material having a modulus of elasticity of 1-4 GPa. The couplingmember 40 may have a modulus of elasticity that is similar to that ofthe high density fiberboard and the medium density fiberboard. When themodulus of elasticity of the coupling member is less than 1 GPa, thecoupling member cannot resist against the stress generated when thefloor boards are contracted by the floor heating, and is easily bent.Therefore, the coupling force at the coupling portion is deteriorated.

The coupling member 40 may be manufactured through an extrusion moldingprocess or an injection molding process. Specifically, a molding processthat can manufacture the coupling members 40 within an error range of0-0.05 mm.

FIG. 8 is a partial sectional view of sectional flooring according to asecond exemplary embodiment of the present invention.

Referring to FIG. 8, sectional flooring 501 of the present exemplaryembodiment is the same as the sectional flooring of the first exemplaryembodiment except that cavities for absorbing thermal expansion of theflooring boards 102 and 201 and the coupling member 40 are formedbetween coupling surfaces of a first floor board 101 and a couplingmember 40 and between a second floor board 201 and the coupling member40.

The cavities 50 function to absorb a repulsive force caused byinterference of cantilever hooks 43 and reduce a gap that is formedbetween the floor boards 101 and 201 by thermal expansion of thecoupling member 40 in the event of the floor heating in a state wherethe coupling member 40 is assembled with the floor boards 101 and 201.The cavities 50 further function to reduce frictional force between thecoupling member 40 and the floor boards 101 and 201 to thereby improvethe work efficiency when the coupling member 40 is assembled with thefloor boards 101 and 201.

Considering the floor heating and the material of the coupling member 40and the floor boards 101 and 201, a width a of the cavities between thecoupling member 40 and the floor boards 101 and 201 at a top surface ofa base portion 41 of the coupling member 40 and the cantilever hook 43may be 0.05-0.20 mm, and a width b of the cavities between the couplingmember 40 and the floor boards 101 and 201 at outer surfaces of the sidehooks 42 may be 0.05-0.50 mm.

FIG. 9 is a partial sectional view of a sectional flooring according toa third exemplary embodiment of the present invention.

Referring to FIG. 9, sectional flooring 502 of the present exemplaryembodiment is the same as the sectional flooring of the first exemplaryembodiment except that an upper portion of a lateral side of each offirst and second floor boards 102 and 202, which does not face acoupling member 40, is formed with a vertical surface. With thisstructure, the upper portion of the lateral side of the first floorboard 102 contacts the upper portion of the lateral side of the secondfloor board 202 without any stopper function.

FIG. 10 is a partial sectional view of a sectional flooring according toa fourth exemplary embodiment of the present invention.

Referring to FIG. 10, sectional flooring 502 of the present exemplaryembodiment is the same as the sectional flooring of the first exemplaryembodiment except that a locking structure formed with a projection 19and a groove 26 is provided on upper portions of lateral sides of firstand second floor boards 103 and 203, which do not face a coupling member40.

That is, the first floor board 103 is provided with the projection 19protruding toward the second floor board 203 and the second floor board203 is provided with a groove 26 for receiving the projection 19.Accordingly, when the first floor board 103 is fitted into the couplingmember 40 by being pressed downward, the projection 19 is engaged withthe groove 26, thereby effectively preventing the movement of the floorboards 103 and 203 in a thickness direction (the z-direction in FIG.10).

FIG. 11 is a partial sectional view of a sectional flooring according toa fifth exemplary embodiment of the present invention.

Referring to FIG. 11, sectional flooring 502 of the present exemplaryembodiment is the same as the sectional flooring of the first exemplaryembodiment except that glue pockets 51 are formed on bottom surfaces,which face a base portion 41 of a coupling member 40, of couplingprotrusions 12 and 22 of respective first and second floor boards 104and 204.

Therefore, when the first floor board 104 is connected to the secondfloor board 204 after an adhesive is applied to a top surface of thebase portion 41 of the coupling member 40, excess adhesive is confinedin the glue pockets 51 and thus a step difference between the floorboards 104 and 204, which is caused by the adhesive, can be prevented.According to this exemplary embodiment, the coupling force by theadhesive and the mechanical coupling force by the coupling member can besimultaneously realized.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. Sectional flooring comprising: first, second, and third floor boardseach having a core formed of wood, the floor boards being provided atlongitudinal and lateral sides with coupling structures and assembledtogether; and a coupling member for connecting the first and secondfloor boards that are arranged to be adjacent to each other in alongitudinal direction thereof, the coupling member being coupled tolower portions of the lateral sides of the first and second floorboards, wherein the coupling member 40 comprises a base portion placedover the adjacent first and second floor boards; a pair of side hooksprotruding from opposite ends of the base portion toward top surfaces ofthe first and second floor boards, the side hooks being fitted in thelateral sides the first and second floor boards to endure a stressapplied in a longitudinal direction of the first and second floorboards; and a pair of cantilever hooks spaced apart from each other by apredetermined distance and protruding from a center of the base portiontoward the top surfaces of the first and second floor boards, each ofthe cantilever hooks including a hook step engaged with the lateral sideof the corresponding one of the first and second floor boards and aninclined portion extending downward from the hook step, the cantileverhooks supporting a stress applied in a thickness direction of the firstand second floor boards, wherein each of the hook steps includes anupper portion formed with a surface that is inclined at a predeterminedlead angle θ_(L) with respect to a vertical line extending in thethickness direction of the first and second floor boards, and a lowerportion formed with a surface that is inclined at a predetermined returnangle θ_(R) with respect to a horizontal line extending in a lengthdirection of the first and second floor boards.
 2. The sectionalflooring of claim 1, wherein the lead angle θ_(L) is 5°˜45° and thereturn angle θ_(R) is equal to or less than 60°.
 3. The sectionalflooring of claim 1, wherein the hook steps and the inclined portionsare provided on outer surfaces of the cantilever hooks, which face theside hooks, and a width of each of the inclined portion is graduallyreduced as it goes away from the base portion.
 4. The sectional flooringof claim 3, wherein a ratio between a lower end width H of thecantilever hook facing the hook step and a lower end width H_(L) of thehook step is about 2:1.
 5. The sectional flooring of claim 1, whereinthe first and second floor board includes: a first recess portion forreceiving the side hook, the first recess portion being formed on alower portion of the lateral side that faces the coupling member; acoupling protrusion, protruding from a side of the first recess portiontoward the lower portion of the first and second floor board and fittedbetween the side hook and the cantilever hook; a second recess portion,that is provided on a side of the coupling protrusion that faces anouter side of the first and second floor board, to receive the hook stepof the cantilever hook; and a projection for guiding a motion of thecantilever hook, the projection being formed with an inclined portion ona lower portion of the second recess portion.
 6. The sectional flooringof claim 5, wherein the coupling protrusion has a width equal to orgreater than 3.0 mm in a longitudinal direction of the first and secondfloor board.
 7. The sectional flooring of claim 5, wherein a cavity forreceiving thermal expansion of the coupling member is formed between thefirst and second floor board and a coupling surface of the couplingmember.
 8. The sectional flooring of claim 7, wherein a width “a” of thecavity between the coupling member and the first and second flooringboard at a top surface of the base portion of the coupling member andthe cantilever hook is 0.05-0.2 mm, and a width “b” of the cavitybetween the coupling member and the first and second floor board at anouter surface of the side hook is 0.05-0.5 mm.
 9. The sectional flooringof claim 5, wherein an upper portion of the lateral side of the firstand second floor board that does not face the coupling member is formedwith a vertical surface, and the vertical surfaces of the first andsecond floor boards and contact each other.
 10. The sectional flooringof claim 5, wherein a stopper projection is formed on an upper portion,which does not face the coupling member of the lateral side of one ofthe first and second floor boards, and a third recess portion forreceiving the stopper projection is formed on an upper portion, whichdoes not face the coupling member, of the lateral side of the other ofthe first and second floor boards.
 11. The sectional flooring of claim5, wherein a protrusion is formed on an upper portion, which does notface the coupling member, of the lateral side of one of the first andsecond floor boards, and a groove is formed on an upper portion, whichdoes not face the coupling member, of the lateral side of the other ofthe first and second floor boards.
 12. The sectional flooring of claim5, wherein a glue pocket is formed on a bottom of the couplingprotrusion that faces the base portion of the coupling members.
 13. Thesectional flooring of claim 5, wherein: the first floor board isprovided at a longitudinal side a with an upper hook step protrudingtoward the third floor board, an intermediate hook step protruding froma bottom of the upper hook step toward a bottom surface thereof, and afourth recess portion provided at a side of the intermediate hook step,which faces an inner portion thereof; and the third floor boards isprovided at the longitudinal side with a fifth recess portion forreceiving the upper hook step, a sixth recess portion for receiving theintermediate hook step, and a lower hook step that extends from thesixth recess portion to an external portion thereof and is received inthe fourth recess portion.
 14. The sectional flooring of claim 1,wherein the floor boards are formed of wood panels, high densityfiberboard, or medium density fiberboard.
 15. The sectional flooring ofclaim 1, wherein the coupling member is formed of a material having amodulus of elasticity of 1˜4 GPa.
 16. A method of assembling thesectional flooring claimed in claim 13, comprising: assembling thesecond floor board with the coupling member; interconnecting thelongitudinal sides a of the first and third floor boards by rotating thefirst floor board downward after fitting the upper hook step of thefirst floor board into the fifth recess portion of the third floorboard; and interconnecting the lateral sides of the first and secondfloor boards by assembling the first floor board with the couplingmember by pressing the first floor board downward.
 17. The method ofclaim 16, wherein when the first floor board is assembled with thecoupling member, the projection biases the cantilever hook toward acenter of the coupling member as the projection of the first floor boardcontacts and slides.